The present invention relates in general to vortex shedding flowmeter circuits and in particular to a new and useful arrangement for reducing vibration noise and sensitivity in vortex shedding flowmeter sensor circuits.
The operation of vortex shedding flowmeters is known and exemplified by U.S. Pat. No. 4,026,150 to Schmidt. It is known that when a non-streamlined obstacle is placed in a flow stream that vortices are produced which alternate from one side to the opposite side of the obstruction. The vortices are produced at a frequency which is directly proportional to the volumetric flow rate.
It is also known to provide a vortex shedding frequency through a preamp to circuitry, and through a two wire transmission line to a remote station for determining the flow rate. Such circuitry is exemplified by U.S. Pat. Nos. 4,134,297 and 4,094,194 to Herzl and 4,123,940 to Herzl et al.
It is known that vortex shedding transmitters are particularly sensitive to vibrations. Such vibrations are sometimes misinterpreted as the vortex shedding frequency or at least represent noise and obstruction to receiving the vortex shedding frequency.